Book Image

Practical Linux Security Cookbook - Second Edition

By : Tajinder Kalsi
Book Image

Practical Linux Security Cookbook - Second Edition

By: Tajinder Kalsi

Overview of this book

Over the last few years, system security has gained a lot of momentum and software professionals are focusing heavily on it. Linux is often treated as a highly secure operating system. However, the reality is that Linux has its share of security ?aws, and these security ?aws allow attackers to get into your system and modify or even destroy your important data. But there’s no need to panic, since there are various mechanisms by which these ?aws can be removed, and this book will help you learn about different types of Linux security to create a more secure Linux system. With a step-by-step recipe approach, the book starts by introducing you to various threats to Linux systems. Then, this book will walk you through customizing the Linux kernel and securing local files. Next, you will move on to managing user authentication both locally and remotely and mitigating network attacks. Later, you will learn about application security and kernel vulnerabilities. You will also learn about patching Bash vulnerability, packet filtering, handling incidents, and monitoring system logs. Finally, you will learn about auditing using system services and performing vulnerability scanning on Linux. By the end of this book, you will be able to secure your Linux systems and create a robust environment.
Table of Contents (20 chapters)
Title Page
Copyright and Credits
Contributors
Packt Upsell
Preface
Index

Security issues – Shellshock


In this era of almost everything being online, online security is a major concern. Nowadays, many web servers, web-connected devices, and services use Linux as their platform. Most versions of Linux use the Unix bash shell so that the Shellshock vulnerability can affect a huge portion of websites and web servers.

In the previous recipe, we understood the details about Shellshock vulnerability. Now, we will understand how this bug can be exploited through SSH.

Getting ready

To exploit Shellshock vulnerability, we need two systems. The first system will be used as the victim's, and should be vulnerable to Shellshock. In our case, we are using an Ubuntu system as the vulnerable system. The second system will be used as the attacker, and can have any Linux version running on it. For our case, we are running Kali on the second system.

The victim system will be running the openssh-server package. It can be installed using the following command:

apt-get install openssh-server...